This invention relates to pivot flow joints for high-pressure flow devices and, more particularly, to pivot flow joints for rotating spray arms mounted on stationary flow members.
Pivot flow joints of the type first mentioned above are known from commonly-owned German Gebrauchsmuster No. G 94 14 482. Such pivot flow joints are used, in particular, in high-pressure cleaning equipment. A rotating (pivoting) part, e.g., a rotating spray arm for flow of high pressure liquid is mounted on a stationary flow member. Such devices, particularly the device of this invention, however, are not limited to use for rotating spray arms of high-pressure cleaning equipment. Such pivot joints can be used in a variety of applications involving flow of high-pressure fluids.
The above-referenced commonly-owned German Gebrauchsmuster 94 14 482 shows the general functioning of such pivot flow joint with sealing arrangements, and because such general functioning is also used in the pivot flow joint of this invention.
The sealing arrangements of such prior pivot flow joints, however, have certain disadvantages, with the result that such prior pivot flow joints did not achieve extended service lives. The period of their usefulness has been limited in time because their sealing arrangement consisted essentially of plastic seals in specific arrangements with O-rings. Because of their sealing arrangements, the rotational speeds of such prior pivot flow joints were limited, as was the temperature of the fluids to be passed through such pivot flow joints.
One object of this invention is to provide an improved pivot flow joint for high-pressure fluids overcoming the problems and shortcomings of prior pivot flow joints.
Another object of this invention is to provide an improved pivot flow joint for high-pressure fluids which permits considerably higher rotational speeds.
Another object of this invention is to provide an improved pivot flow joint for high-pressure fluids which permits flow of fluids at higher temperatures and allows high rotational speeds with such fluids.
Still another object of this invention is to provide an improved pivot flow joint for high-pressure fluids which allows extended service lives, while still providing the other advantages mentioned above.
These and other objects of the invention will be apparent from the following descriptions and from the drawings.
The invention is a pivot flow joint for high-pressure fluids which overcomes the above problemsxe2x80x94allowing a considerably higher rotational speed at higher fluid temperatures over a considerably longer service life.
The device of the invention includes two sealing, oppositely-acting seal bushings arranged between non-rotating and rotating flow members. Each of the two seal bushings is secured to the corresponding flow member and the two seal bushings tightly adjoin one another in sealed engagementxe2x80x94preferably at a flat plane. That is, each seal bushing has a contact surface in tight engagement with the corresponding contact surface of the other seal bushing.
It is important that this contact plane be perpendicular to the direction of flow of the high-pressure fluid and extend radially with respect to the axis defined by the pivot flow joint.
In a preferred embodiment of the invention it is provided that each of the seal bushings be of a ceramic material. However, instead of a ceramic material, it is also possible for other materials to be used for the seal bushings; examples of acceptable materials include a sintered metal, a metal-plastic composite material, a hard metal or a ceramic composite material.
As indicated, the invention involves replacing known seals by two seal bushings contacting one another at adjoining contact surfaces. The seal bushings may be made to be mirror images of one another. It is preferred that the two seal bushings be spring-loaded against one another in their contact surface. The spring loading here is preferably achieved by two wave spring washers arranged on the sides of the seal bushings away from their contact surfaces; such spring washers cause the two seal bushings to abut one another under spring tension at the contact plane.
Each of the two seal bushings is sealed against its respective flow member (i.e., the non-rotating flow member or the rotating flow member) by an O-ring against the flow member.
The arrangement of bearings between rotating and non-rotating portions of the pivot flow device plays no essential role for the success of the invention, broadly defined. Thus, a variety of bearing arrangements can be used. One particularly preferred configuration includes at least one thrust bearing with axial grooved discs in position arranged two separated deep-groove ball bearings.
In one refinement of the invention the seal bushings are configured near their contact surfaces in a manner which serves to conduct fluid in the area of the contact surfaces toward a relief hole in an enclosing sleeve or otherwise to a relief channel, depending on the outer configuration of the pivot flow joint. Thus, if there should be a failure of the sealing engagement of the two seal bushings, any fluid building up will be diverted to the exterior via the relief hole, rather than reach the interior area where the bearings are housed, which could damage the bearings.
Failures from wear and tear can occur only after very long running times. However, when and if any such failure occurs, the escape of fluid through the relief hole allows one to recognize that the seal bushings are worn; thus, they can then be replaced at the appropriate time.
With the present invention, which provides two seal bushings engaging one another under spring loading, an easily rotating pivot flow joint is provided. When compared to prior devices, the pivot flow joint of this invention has a considerably longer service life, at a higher rotational speed and higher temperatures of the high-pressure fluid which is flowing.
It should also be especially noted that the pivot flow joint of this invention can be used not just with aqueous fluids, but with non-aqueous high-pressure fluids. The pivot flow joint of this invention can be used in situations involving pressures of up to 300 bar and temperatures between 5 and 200xc2x0 C., and at such pressures and temperatures can operate at speeds as high as 2000 rpm. Furthermore, the fluid may have a pH anywhere within the range of 3 to 12. The aforementioned values for various parameters are merely exemplary, and may be considerably exceeded.
The performance of the pivot flow joint of this invention results not only from features of individual claims, but from combinations of the features of the invention. All specifications and characteristics disclosed in this document, including in the abstract, and in particular the configurations represented in the drawings, are set forth as not claimed as essential to the invention.
The invention is also described as an improvement in pivot flow joints for high-pressure fluid-flow devices of the type including a rotating flow member connected to a non-rotating flow member. The improvement includes first and second axially-aligned seal bushings secured to the non-rotating and rotating flow members, respectively, the first and second seal bushings having opposed adjoining contact surfaces and being biased toward one another for sealing engagement at such contact surfaces.
In highly preferred embodiments, the seal bushings are configured and arranged such that the high-pressure fluid in the pivot flow joint exerts axial pressure biasing the seal bushings toward one another. It is also preferred that the first and second bushings be spring-biased toward one another.
The first and second seal bushings are preferably sealed by O-rings against the non-rotating and rotating flow members, respectively. The pivot flow joint also preferably includes a sleeve over the rotatable flow member which encloses the seal bushings. The rotatable flow member is seated radially against the sleeve by first bearings which facilitate rotation of the rotatable flow member with respect to the sleeve. Such a sleeve most preferably has a relief hole therethrough to allow outflow of fluid, such that any incipient non-integrity of the pivot flow joint can be noted. The rotatable flow member is also seated axially against the sleeve by a thrust bearing that further facilitates rotation of the rotatable flow member with respect to the sleeve. The pivot flow joint also preferably includes sealing devices which serve to isolate all of the bearings to protect them against the intrusion of moisture.
The non-rotating flow member of the pivot flow joint has an inflow side which includes a device for connection to the high-pressure fluid supply, and the rotating flow member has an outflow side which includes a device for connection to a rotating device to be operated.
The contact surfaces of the first and second seal bushings are preferably flat annular surfaces. The first and second seal bushings are preferably formed of ceramic material, as noted above, and they are most preferably of identical shape and size.
In preferred embodiments, the first seal bushing is non-rotatably secured with respect to the non-rotating flow member, and the second seal bushing is non-rotatably secured with respect to the rotatable flow member such that the second seal bushing and rotatable flow member rotate together.
More broadly, the invention is an improvement in pivot flow joints of the type including relatively-rotatable first and second flow members, the improvement involving first and second axially-aligned seal bushings (as described above) secured to the first and second flow members, respectively. As described above, the first and second seal bushings have opposed adjoining contact surfaces and are biased toward one another for sealing engagement at such contact surfaces.
The invention is explained in greater detail below on the basis of drawings illustrating only one route of embodiment. Additional essential characteristics and advantages of the invention are evident from the drawings and the description thereof.